Japanese Patent Application Publication No. 2014-137298 discloses a device that detects a liquid level of fuel in a fuel tank. This device includes a body, a magnet holder rotatably held by the body, a magnet that integrally rotates with the magnet holder, a float that floats on a surface of the fuel, an arm that has one end to which the float is fixed, and the other end to which the magnet holder is fixed, and a Hall element housed in the body.
The magnet holder has a shaft hole disposed on a rotational axis. The body has a shaft portion fitted into the shaft hole of the magnet holder. A slight clearance is provided along an entire circumference between an outer circumference surface of the shaft portion and an inner circumference surface of the shaft hole. A portion of the inner circumference surface of the shaft hole slides relative to the outer circumference surface of the shaft portion to thereby cause the magnet holder to rotatably move relative to the body. The magnet holder is configured of POM (i.e., polyacetal), and the body is configured of PPS (i.e., polyphenylene sulfide).